The term “soil release polymer” is used in the art to cover polymeric materials which assist release of soil from fabrics, e.g. cotton or polyester based fabrics. For example, it is used in relation to polymers which assist release of soil direct from fibres. It is also used to refer to polymers which modify the fibres so that dirt adheres to the polymer-modified fibres rather than to the fibre material itself. Then, when the fabric is washed the next time, the dirt is more easily removed than if it was adhering the fibres. Although not wishing to be bound by any particular theory or explanation, the inventors believe that the soil release polymers utilised in the present invention probably exert their effect mainly by the latter mechanism.
The compounds utilised by the present invention have been found, dependent upon the structure of the compound in question, to deliver a soil release, fabric care and/or other laundry cleaning benefit.
The deposition of a benefit agent onto a substrate, such as a fabric, is well known in the art. In laundry applications typical “benefit agents” include fabric softeners and conditioners, soil release polymers, sunscreens; and the like. Deposition of a benefit agent is used, for example, in fabric treatment processes such as fabric softening to impart desirable properties to the fabric substrate.
Conventionally, the deposition of the benefit agent has had to rely upon the attractive forces between the oppositely charged substrate and the benefit agent. Typically this requires the addition of benefit agents during the rinsing step of a treatment process so as to avoid adverse effects from other charged chemical species present in the treatment compositions. For example, cationic fabric conditioners are incompatible with anionic surfactants in laundry washing compositions.
Such adverse charge considerations can place severe limitations upon the inclusion of benefit agents in compositions where an active component thereof is of an opposite charge to that of the benefit agent. For example, cotton is negatively charged and thus requires a positively charged benefit agent in order for the benefit agent to be substantive to the cotton, i.e. to have an affinity for the cotton so as to absorb onto it. Often the substantivity of the benefit agent is reduced and/or the deposition rate of the material is reduced because of the presence of incompatible charged species in the compositions.
WO-A-97/42285 discloses cotton soil-release polymers comprising a polyamine backbone and quaternary ammonium cationic groups. However, the present applicants have found that, whilst cationic groups give good substantivity to cotton, a high density of cationic positive changes on the polymer gives rise to staining of the fabric.
Thus, there remains a need to obtain soil release in laundry products based on soil-release agents which give better substantivity to cotton and therefore better soil release from cotton fabrics, fewer or no detrimental interactions with LAS or other anionic surfactants, as well as less staining negatives.